Randomly slow internet speed in domain environment

Riccochet

Riccochet

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Apr 11, 2007
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Didn't know where else to put this, so here it is.

Server 2003R2 domain environment. AD, DNS, DHCP all being done by server. Roughly 20 pc's on the network. Cisco Catalyst 2950 switch, Sonicwall TZ190 firewall, 20/5 cable internet service. PC's on domain get extremely slow internet speeds, as in .5 to 5mbps down and .5 to 5mbps up. Server is handling DNS and doing the forwarding. Strange thing is sometimes a PC will get the full 20/5, and then minutes later go back to being crappy. We've taken a laptop on sight and no matter where it's plugged in via patch cable, and pulling DHCP from the server, gets full 20/5. Removed PC's from the domain and that doesn't work. DNS is properly set up. There is no difference in IP settings between PC's on the domain and off it. All pc's using MSE for anti-virus. No proxy servers or gateway software nor any web filtering going on.

This has been killing me for the past couple weeks. None of it makes any damn sense. Hopefully someone here has been down this road before.

Please no "upgrade that server". It's a clients server and it'll be EOL'd in 6 months as we transition them to our hosting environment.
 
Is it a load issue on the Sonicwall? Pull up the interface and watch the CPU. Run a ping to it simultaneously (and other network devices if possible) to see what is taking a hit while performing speedtests.
 
ryang said:
Is it a load issue on the Sonicwall? Pull up the interface and watch the CPU. Run a ping to it simultaneously (and other network devices if possible) to see what is taking a hit while performing speedtests.
Click to expand...

We looked at that last night. Sonicwall is barely being taxed. Even after hours when no one is in the office using the network internet speeds are slow.

Doing nslookup's come back very quick. So name resolution is not an issue. dnslint report doesn't show any errors. dcdiag also comes back clean. tracert's to random sites doesn't show any lags. It's like throughput is being capped or managed somewhere, but then it goes away, and comes back.

Strange strange strange things are afoot the network.
 
Are the forwarders setup right in DNS? If so what are you using for a DNS server? OpenDNS?
 
This isn't as hard to figure out as you would think.

Do you have full speed access to other shares when the internet speed related issue is occurring?

If Yes, the problem is either the sonicwall, the cable modem or the ISP.

If no, the problem is on the local PC....start looking at the behavior of the local AV insall, switch configurations, GPO implementations etc.


Also FYI... MSE is not legally licensable for a business over 10 PCs, over 10 PCs you're supposed to use Microsoft System Center 2012 Endpoint Protection.
 
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